read_me

早期freebsd实现

# Copyright (c) 1983 Eric P. Allman
# Copyright (c) 1988 The Regents of the University of California.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. All advertising materials mentioning features or use of this software
#    must display the following acknowledgement:
#	This product includes software developed by the University of
#	California, Berkeley and its contributors.
# 4. Neither the name of the University nor the names of its contributors
#    may be used to endorse or promote products derived from this software
#    without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
#	@(#)READ_ME	8.61 (Berkeley) 4/17/94
#

This directory contains the source files for sendmail.

For detailed instructions, please read the document ../doc/op.me:

	eqn ../doc/op.me | pic | ditroff -me

The Makefile is for the new (4.4BSD) Berkeley make and uses syntax
that is not recognized by older makes.  It also has assumptions
about the 4.4 file system layout built in.  See below for details
about other Makefiles.

There is also a Makefile.dist which is much less clever, but works on
the old traditional make.  You can use this using:

	make -f Makefile.dist

**************************************************
**  Read below for more details of Makefiles.	**
**************************************************

There is also a shell script (makesendmail) that tries to be clever
about using object subdirectories.  It's pretty straightforward, and
may help if you share a source tree among different architectures.

**************************************************************************
**  IMPORTANT:  DO NOT USE OPTIMIZATION (``-O'') IF YOU ARE RUNNING	**
**  GCC 2.4.x or 2.5.x.  THERE IS A BUG IN THE GCC OPTIMIZER THAT	**
**  CAUSES SENDMAIL COMPILES TO FAIL MISERABLY.				**
**************************************************************************

Jim Wilson of Cygnus believes he has found the problem -- it will
probably be fixed in GCC 2.5.6 -- but until this is verified, be
very suspicious of gcc -O.

**************************************************************************
**  IMPORTANT:  Read the appropriate paragraphs in the section on	**
**  ``Operating System and Compile Quirks''.				**
**************************************************************************


+-----------+
| MAKEFILES |
+-----------+

The "Makefile"s in these directories are from 4.4 BSD, and hence
really only work properly if you are on a 4.4 system.  In particular,
they use new syntax that will not be recognized on old make programs,
and some of them do things like ``.include ../../Makefile.inc'' to
pick up some system defines.  If you are getting sendmail separately,
these files won't be included in the distribution, as they are
outside of the sendmail tree.

Instead, you should use one of the other Makefiles, such as
Makefile.SunOS for a SunOS system, and so forth.  These should
work with the version of make that is appropriate for that
system.

There are a bunch of other Makefiles for other systems with names
like Makefile.HPUX for an HP-UX system.  They use the version of
make that is native for that system.  These are the Makefiles that
I use, and they have "Berkeley quirks" in them.  I can't guarantee
that they will work unmodified in your environment.  Many of them
include -I/usr/sww/include/db and -L/usr/sww/lib -- this is Berkeley's
location (the ``Software Warehouse'') for the new database libraries,
described below.  You don't have to remove these definitions if you
don't have these directories.

Please look for an appropriate Makefile before you start trying to
compile with Makefile or Makefile.dist.

If you want to port the new Berkeley make, you can get it from
ftp.uu.net in the directory /systems/unix/bsd-sources/usr.bin/make.
Diffs and instructions for building this version of make under
SunOS 4.1.x are available on ftp.css.itd.umich.edu in
/pub/systems/sun/Net2-make.sun4.diff.Z.  Diffs and instructions
for building this version of make under IBM AIX 3.2.4 are available
on ftp.uni-stuttgart.de in /sw/src/patches/bsd-make-rus-patches.
Paul Southworth <[e-mail]> published a description of porting
this make in comp.unix.bsd.

The complete text of the Makefile.inc that is in the parent of the
sendmail directory is:

	#	@(#)Makefile.inc	8.1 (Berkeley) 6/6/93

	BINDIR?=	/usr/sbin


+----------------------+
| DATABASE DEFINITIONS |
+----------------------+

There are several database formats that can be used for the alias files
and for general maps.  When used for alias files they interact in an
attempt to be back compatible.

The three options are NEWDB (the new Berkeley DB package), NDBM (the
older DBM implementation -- the very old V7 implementation is no
longer supported), and NIS (Network Information Services).  Used alone
these just include the support they indicate.  [If you are using NEWDB,
get the latest version from FTP.CS.Berkeley.EDU in /ucb/4bsd.  DO NOT
use the version from the Net2 distribution!  However, if you are on
BSD/386 or 386BSD-based systems, use the one that already exists
on your system.  You may need to #define OLD_NEWDB 1 to do this.]

[NOTE WELL: it is CRITICAL that you remove ndbm.o from libdb.a and
ndbm.h from the appropriate include directories if you want to get
ndbm support.  These files OVERRIDE calls to ndbm routines -- in
particular, if you leave ndbm.h in, you can find yourself using
the new db package even if you don't define NEWDB.]

If NEWDB and NDBM are defined (but not NIS), then sendmail will read
NDBM format alias files, but the next time a newaliases is run the
format will be converted to NEWDB; that format will be used forever
more.  This is intended as a transition feature.  [Note however that
the NEWDB library also catches and maps NDBM calls; you will have to
back out this feature to get this to work.  See ``Quirks'' section
below for details.]

If all three are defined, sendmail operates as described above, and also
looks for the file /var/yp/Makefile.  If it exists, newaliases will
build BOTH the NEWDB and NDBM format alias files.  However, it will
only use the NEWDB file; the NDBM format file is used only by the
NIS subsystem.

If NDBM and NIS are defined (regardless of the definition of NEWDB
or the existance of /var/yp/Makefile), sendmail adds the special
tokens "YP_LAST_MODIFIED" and "YP_MASTER_NAME", both of which are
required if the NDBM file is to be used as an NIS map.

All of -DNEWDB, -DNDBM, and -DNIS are normally defined in the DBMDEF
line in the Makefile.


+---------------+
| COMPILE FLAGS |
+---------------+

Whereever possible, I try to make sendmail pull in the correct
compilation options needed to compile on various environments based on
automatically defined symbols.  Some machines don't seem to have useful
symbols availble, requiring the following compilation flags in the
Makefile:

SOLARIS		Define this if you are running Solaris 2.0 or higher.
SOLARIS_2_3	Define this if you are running Solaris 2.3 or higher.
SUNOS403	Define this if you are running SunOS 4.0.3.
NeXT		Define this if you are on a NeXT box.  (This one may
		be pre-defined for you.)  There are other hacks you
		have to make -- see below.
_AIX3		Define this if you are IBM AIX 3.x.
RISCOS		Define this if you are running RISC/os from MIPS.
IRIX		Define this if you are running IRIX from SGI.
_SCO_unix_	Define this if you are on SCO UNIX.
_SCO_unix_4_2	Define this if you are on SCO Open Server 3.2v4.

If you are a system that sendmail has already been ported to, you
probably won't have to touch these.  But if you are porting, you may
have to tweak the following compilation flags in conf.h in order to
get it to compile and link properly:

SYSTEM5		Adjust for System V (not necessarily Release 4).
SYS5SIGNALS	Use System V signal semantics -- the signal handler
		is automatically dropped when the signal is caught.
		If this is not set, use POSIX/BSD semantics, where the
		signal handler stays in force until an exec or an
		explicit delete.  Implied by SYSTEM5.
SYS5SETPGRP	Use System V setpgrp() semantics.  Implied by SYSTEM5.
HASFLOCK	Set this if you prefer to use the flock(2) system call
		rather than using fcntl-based locking.  Fcntl locking
		has some semantic gotchas, but many vendor systems
		also interface it to lockd(8) to do NFS-style locking.
		For this reason, this should not be set unless you
		don't have an alternative.
HASUNAME	Set if you have the "uname" system call.  Implied by
		SYSTEM5.
HASUNSETENV	Define this if your system library has the "unsetenv"
		subroutine.
HASSETSID	Define this if you have the setsid(2) system call.  This
		is implied if your system appears to be POSIX compliant.
HASINITGROUPS	Define this if you have the initgroups(3) routine.
HASSETVBUF	Define this if you have the setvbuf(3) library call.
		If you don't, setlinebuf will be used instead.  This
		defaults on if your compiler defines __STDC__.
HASSETREUID	Define this if you have setreuid(2) ***AND*** root can
		use setreuid to change to an arbitrary user.  This second
		condition is not satisfied on AIX 3.x.  You may find that
		your system has setresuid(2), (for example, on HP-UX) in
		which case you will also have to #define setreuid(r, e)
		to be the appropriate call.  Some systems (such as Solaris)
		have a compatibility routine that doesn't work properly,
		but may have "saved user ids" properly implemented so you
		can ``#define setreuid(r, e) seteuid(e)'' and have it work.
		The important thing is that you have a call that will set
		the effective uid independently of the real or saved uid
		and be able to set the effective uid back again when done.
		There's a test program in ../test/t_setreuid.c that will
		try things on your system.  Setting this improves the
		security, since sendmail doesn't have to read .forward
		and :include: files as root.  There are certain attacks
		that may be unpreventable without this call.
HASLSTAT	Define this if you have symbolic links (and thus the
		lstat(2) system call).  This improves security.  Unlike
		most other options, this one is on by default, so you
		need to #undef it in conf.h if you don't have symbolic
		links (these days everyone does).
NEEDGETOPT	Define this if you need a reimplementation of getopt(3).
		On some systems, getopt does very odd things if called
		to scan the arguments twice.  This flag will ask sendmail
		to compile in a local version of getopt that works
		properly.
NEEDSTRTOL	Define this if your standard C library does not define
		strtol(3).  This will compile in a local version.
NEEDVPRINTF	Define this if your standard C library does not define
		vprintf(3).  Note that the resulting fake implementation
		is not very elegant and may not even work on some
		architectures.
NEEDFSYNC	Define this if your standard C library does not define
		fsync(2).  This will try to simulate the operation using
		fcntl(2); if that is not available it does nothing, which
		isn't great, but at least it compiles and runs.
HASGETUSERSHELL	Define this to 1 if you have getusershell(3) in your
		standard C library.  If this is not defined, or is defined
		to be 0, sendmail will scan the /etc/shells file (no
		NIS-style support, defaults to /bin/sh and /bin/csh if
		that file does not exist) to get a list of unrestricted
		user shells.  This is used to determine whether users
		are allowed to forward their mail to a program or a file.
GIDSET_T	The type of entries in a gidset passed as the second
		argument to getgroups(2).  Historically this has been an
		int, so this is the default, but some systems (such as
		IRIX) pass it as a gid_t, which is an unsigned short.
		This will make a difference, so it is important to get
		this right!  However, it is only an issue if you have
		group sets.
SLEEP_T		The type returned by the system sleep() function.
		Defaults to "unsigned int".  Don't worry about this
		if you don't have compilation problems.
ARBPTR_T	The type of an arbitrary pointer -- defaults to "void *".
		If you are an very old compiler you may need to define
		this to be "char *".
LA_TYPE		The type of load average your kernel supports.  These
		can be one of:
		LA_ZERO (1) -- it always returns the load average as
			"zero" (and does so on all architectures).
		LA_SUBR (4) if you have the getloadavg(3) routine,
		LA_MACH (5) to use MACH-style load averages (calls
			processor_set_info()),
		LA_PROCSTR (7) to read /proc/loadavg and interpret it
			as a string representing a floating-point
			number (Linux-style),
		LA_FLOAT (3) if you read kmem and interpret the value
			as a floating point number,
		LA_INT (2) to interpret as a long integer,
		LA_SHORT (6) to interpret as a short integer.
		These last three have several other parameters that they